KROHNE BM 70 M - Manual (Page 24)

24 BM 70 M
6.4 Maintenance
Cleaning the antenna
Particular process applications can cause severe contamination of the antenna. Microwaves
cannot be properly emitted or received when reflected from deposits on the antenna. In such
cases, the BM 70 M will usually indicate maximum level (volume) or minimum distance.
The level of contamination at which such errors occur depends firstly on the product concerned,
and secondly on the reflection index, which is mainly determined
E\WKHUHODWLYHSHUPLWWLYLW\0
r
.
Regular cleaning, or use of the purging device (see Sect. 6.1.7), is advisable if the product has a
tendency to form deposits, etc.
When spraying, washing down, or cleaning with mechanical aids, take special care not to
damage either the horn antenna or the bottom Teflon plug at the waveguide window (see Section
7.3 "Field assembly of the BM 70 M"). If cleaning agents are used, take material resistance into
account!
7 Design
Hazardous-duty systems
The BM 70 M-Ex is approved to European Standard EN 50014/18/19/20 for use in hazardous
locations of Zones 0, 1 and 2.
Electronics compartment Flameproof Enclosure "d"
Terminal compartment Increased Safety "e" for signal output and power supply
Optionally: Intrinsic Safety "i" for the signal output and
Increased Safety "e" for the power supply.
Special version: Flameproof Enclosure "d"
Pin coupler compartment Increased Safety "e"
Further details are given in the Certificates of Conformity, see Section 10.
7.1 Dimensions and weights
SA version V96 version